Building a partition wall

[Bird In Hand]

We have a 3-floor Colonial with a center hall/stairway.  The third floor/attic is a finished walk-up, and the walls of the stairway are half-height (actually 36").  So you can stand at one gable end of the attic and look across the stairway half-walls to see the other gable end.  An open floor plan, in a sense.  The roof is 12-pitch with attic trusses, so a little under 8 feet at the center for several feet, and then sloping down to knee walls on either side.

The larger side we use as an office and lounging area, and the smaller side we use as a sleeping area for one of the kids.

We're thinking about extending one of the stair walls to the ceiling -- probably the one flanking the smaller space, to make that a little more private and room-like.  It won't be a real room, because it won't have a door; it will just be open from the top of the stairs to the sloping ceiling that meets the knee wall about eight feet past the top of the stairs.

It seems like it wouldn't be super hard to do this.  Basically remove the 1x6 painted wood cap that sits on top of the half-height wall, then build a 2x4 wall frame that attaches to the top plate of the stair wall and to the ceiling.

The only tricky parts I see are 1) one side of the frame will be at a 45-degree angle to match the sloping ceiling, and 2) the top of the frame runs parallel with the attic trusses and is exceedingly unlikely to line up with one.  So I'll probably need to cut into the ceiling (drywall) and attach braces between the nearest two trusses to give the frame  some attachment points.

I have very basic carpentry skills, and equipment for building a frame.  Is this something worth figuring out on my own, or are there some obvious pitfalls that would push the needle toward hiring this out?

In my limited experience with drywall and finishing work, I know that I'd almost certainly hire out that part of the job.

[sonofsven]

I'll try to keep it brief:

First off, I would recommend you not try to build the new wall on the half wall, build your new wall all the way to the floor. Anything wrong with the half wall will also be wrong with the new wall.

Remove drywall  where the top plate of your wall will be all the way from the rafter/truss on one side of the proposed top plate to the rafter/truss on the other side of the top plate  and install blocks between the rafter/truss and flush with them, 2x4 or 2x6, doesn't matter.

Place the blocks at 4' on center spacing or whatever makes sense close to the pitch change.

I snap lines for everything but if you're careful you can just temporarily attach your bottom plate where you want the wall to be, the bottom plate is the overall length of the wall, one piece ideally, and somewhat straight. If you snap lines you can bend the plate to your line as needed.

Now you need to transfer the location of the bottom plate to the blocks. There's multiple ways to do this:  Laser level with a plumb feature, level against a straight board, two overlapping levels for different heights, a plumb bob...

With marks on the blocks attach the top plate. I use construction screws in case it needs adjustment.

It sounds like there will be two sections of top plate; remember, this is framing and the joints don't have to be perfect.

Now lay out your bottom plate for studs at 16" on center and transfer those marks to the top plate.

Measure, cut, and install each stud. Measure to the long side.

Add 2x between the blocks as bearing for the drywall. You could try to cut the drywall back to the center of each truss/joist/rafter, but that's where it's nailed so it's not much fun.

All the different blocks etc should plane out nicely for a good drywall job.

I think that's about it.

[Bird In Hand]

Thanks @sonofsven, I appreciate the detailed response.

I was hoping to avoid tearing down the existing half-height wall (I think it's actually ~42", not 36") and starting over.  The main reason is that the existing wall is already in the right spot, and halfway complete.  :)  But I'm also wary of all the small details like the existing baseboard trim, stair skirtboard, and the display shelf that spans the stair walls above the doorway at the bottom of the stairs.  Oh, and the existing wall has electrical running through it, with an outlet.

I know none of the above items are dealbreakers to a carpenter or someone with more construction experience, but they are certainly impediments that make it less of an appealing DIY project for me.

Regardless of approach, I'm also concerned about issues I might have cutting in to the drywall ceiling.  I know there is electrical there to the two attic ceiling lights, as well as the (wired) smoke detector.  I don't think there's a vapor barrier in the ceiling, but I suppose I'd find out soon enough :o  I assume there are fiberglass batts up there.

[theoverlook]

I don't see any reason to tear down the existing knee wall. If it's in good shape, it's definitely not going to be overloaded just by having some drywall and framing put on top of it.

How long is the knee wall that you're hoping to extend to the ceiling? I would be tempted to frame it out with metal and insulate it for noise control. Metal is lighter and cleaner to work with so you can cut it in the space rather than having to carry pieces all the way outside or do a ton of cleanup from cutting 2x4s in a finished space. Do you have tin snips? That's all you need to cut metal studs and track.

Drywall finishing is a pain and I can understand farming that out.

This is literally just a room divider that happens to be built in place. I don't think there's any call for stripping drywall back to the roof trusses and putting in full width blocking. Using a plumb bob or laser line you can mark the center of your knee wall on the ceiling. Then drill pilot holes - making sure not to drill through your roof! If there's no wood back there, use a good anchor I'm really fond of Togglers "Snap Toggle" anchors. Not toggle bolts, but these guys:



They're insanely strong and you can have a bit of adjustability by drilling the holes through your 2x4s or metal studs a bit oversized.

Once the top is anchored in place with those and the bottom is secured to the knee wall, what on earth is going to happen to it to make it a problem?

[zolotiyeruki]

Does it have to be a wall?

I'll just toss this idea out there--if your need is for visual separation, could a curtain serve the purpose?

If you're needing sound isolation as well, I can understand the desire to build a wall all the way to the rafters, but since there's no door involved, that doesn't seem to apply.

[sonofsven]

Ok, full disclaimer, my response is based on my profession as a carpenter. That is how I would approach it, but perhaps it is too much for a diy thread?
Hopefully someone will find it valuable.

[Bird In Hand]

@theoverlook, thanks for the idea.  Those snap toggles look pretty handy!  In this case I'd worry that heat expansion/contraction of the attic ceiling would end up ruining the drywall tape & mud at the wall/ceiling junction.

@zolotiyeruki, my wife wants a wall so we can paint it, hang things on it, etc.  Having a curtain up there might provide a quick way to get a feel for what the space would be like with a partition though -- nice idea.

@sonofsven, your response as a carpenter is definitely welcomed.  Though, as I mentioned above, some things that would be trivial to you are things that would make the ideal approach (starting from the floor up) rather vexing to me (arg, trim work!).  But you do have me thinking about what might go wrong building the 2nd half of the wall upon a 1st have that has issues.

Let me ask you this: if you examined the lower half of the wall and found it to be fundamentally sound/plumb/etc., would you consider building the 2nd half on top?  Or does your experience tell you that there are too many things that can go wrong?

[Papa bear]

I don't see any reason to tear down the existing knee wall. If it's in good shape, it's definitely not going to be overloaded just by having some drywall and framing put on top of it.

How long is the knee wall that you're hoping to extend to the ceiling? I would be tempted to frame it out with metal and insulate it for noise control. Metal is lighter and cleaner to work with so you can cut it in the space rather than having to carry pieces all the way outside or do a ton of cleanup from cutting 2x4s in a finished space. Do you have tin snips? That's all you need to cut metal studs and track.

Drywall finishing is a pain and I can understand farming that out.

This is literally just a room divider that happens to be built in place. I don't think there's any call for stripping drywall back to the roof trusses and putting in full width blocking. Using a plumb bob or laser line you can mark the center of your knee wall on the ceiling. Then drill pilot holes - making sure not to drill through your roof! If there's no wood back there, use a good anchor I'm really fond of Togglers "Snap Toggle" anchors. Not toggle bolts, but these guys:



They're insanely strong and you can have a bit of adjustability by drilling the holes through your 2x4s or metal studs a bit oversized.

Once the top is anchored in place with those and the bottom is secured to the knee wall, what on earth is going to happen to it to make it a problem?

Holy shit this scares the crap out of me.  This is taking about building a wall next to a staircase.   This isn’t just a partition in the middle of the room.  I can just imagine an accident with kids tough housing or a couple guys leaning on the wall and the thing failing.  When you expect a wall, it should be a wall. It shouldn’t be held by drywall.  With just a kneewall, someone would know not to wrestle on it or bounce off of it.  When it’s all a wall? You have no way of knowing it’s unsafe.

Sonofseven has the correct way to build this.  Do this one right or someone will be cursing your name in the future. 


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[theoverlook]

Holy shit this scares the crap out of me.  This is taking about building a wall next to a staircase.   This isn’t just a partition in the middle of the room.  I can just imagine an accident with kids tough housing or a couple guys leaning on the wall and the thing failing.  When you expect a wall, it should be a wall. It shouldn’t be held by drywall.  With just a kneewall, someone would know not to wrestle on it or bounce off of it.  When it’s all a wall? You have no way of knowing it’s unsafe.

Sonofseven has the correct way to build this.  Do this one right or someone will be cursing your name in the future. 


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They hang railings on those snap toggles, hung in nothing but drywall, and they pass inspections and hold up for decades without issue. Each snaptoggle is rated for 265lb load in 1/2" drywall. Not to mention the bottom would be screwed securely into the wood of the knee wall. I think you're severely underestimating the strength of drywall or overestimating the weight of humans.

[GuitarStv]

Holy shit this scares the crap out of me.  This is taking about building a wall next to a staircase.   This isn’t just a partition in the middle of the room.  I can just imagine an accident with kids tough housing or a couple guys leaning on the wall and the thing failing.  When you expect a wall, it should be a wall. It shouldn’t be held by drywall.  With just a kneewall, someone would know not to wrestle on it or bounce off of it.  When it’s all a wall? You have no way of knowing it’s unsafe.

Sonofseven has the correct way to build this.  Do this one right or someone will be cursing your name in the future. 


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They hang railings on those snap toggles, hung in nothing but drywall, and they pass inspections and hold up for decades without issue. Each snaptoggle is rated for 265lb load in 1/2" drywall. Not to mention the bottom would be screwed securely into the wood of the knee wall. I think you're severely underestimating the strength of drywall or overestimating the weight of humans.

I know that they hang railings on those snap in anchors.  How do I know?  Several years ago I slipped while heading down the stairs, grabbed the railing hard, and the whole railing tore out (three of those anchors) and fell on top of my face (giving me a pretty good fat lip) as I slid down the hard wood stairs on my ass.  Made a giant mess of the wall where they ripped out too.

It's only one data point, but I'd never rely on those.

[Papa bear]

Holy shit this scares the crap out of me.  This is taking about building a wall next to a staircase.   This isn’t just a partition in the middle of the room.  I can just imagine an accident with kids tough housing or a couple guys leaning on the wall and the thing failing.  When you expect a wall, it should be a wall. It shouldn’t be held by drywall.  With just a kneewall, someone would know not to wrestle on it or bounce off of it.  When it’s all a wall? You have no way of knowing it’s unsafe.

Sonofseven has the correct way to build this.  Do this one right or someone will be cursing your name in the future. 


Sent from my iPhone using Tapatalk

They hang railings on those snap toggles, hung in nothing but drywall, and they pass inspections and hold up for decades without issue. Each snaptoggle is rated for 265lb load in 1/2" drywall. Not to mention the bottom would be screwed securely into the wood of the knee wall. I think you're severely underestimating the strength of drywall or overestimating the weight of humans.

I have rentals.  Nothing is impossible.


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[ChickenStash]

If I wanted it to look, feel, act, and smell like a normal wall in the house then I would build it like the rest of the walls so there are no unhappy surprises. I could maybe see building onto the existing knee wall to save some effort but I would prefer to build it over as a single unit.

For a more official answer, check with your city or county building inspectors. They will know the local building codes.